721724243809 has 2 divisors, whose sum is σ = 721724243810. Its totient is φ = 721724243808.

The previous prime is 721724243771. The next prime is 721724243819. The reversal of 721724243809 is 908342427127.

721724243809 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 413223980625 + 308500263184 = 642825^2 + 555428^2 .

It is a cyclic number.

It is not a de Polignac number, because 721724243809 - 2¹¹ = 721724241761 is a prime.

It is not a weakly prime, because it can be changed into another prime (721724243819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360862121904 + 360862121905.

It is an arithmetic number, because the mean of its divisors is an integer number (360862121905).

Almost surely, 2^721724243809 is an apocalyptic number.

It is an amenable number.

721724243809 is a deficient number, since it is larger than the sum of its proper divisors (1).

721724243809 is an equidigital number, since it uses as much as digits as its factorization.

721724243809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1354752, while the sum is 49.

The spelling of 721724243809 in words is "seven hundred twenty-one billion, seven hundred twenty-four million, two hundred forty-three thousand, eight hundred nine".